1. Field of the Invention
This invention relates to apparatus including a single compartment cabinet housing having electrical terminal assembly mounted on the back wall of the cabinet to engage plug-in modular assemblies including a power fuse assembly, a contactor assembly and an isolating switch assembly of a high voltage starter.
2. Description of the Prior Art
A high voltage starter is employed for starting and controlling AC motors with voltages ranging from 2500 to 5000 volts. This industrial type controller is designed to be installed, operated, and maintained by adequately trained workmen. For safety reasons, high voltage motor controllers require an isolating switch to provide a mechanical opening of the power circuit to permit maintenance. It is expedient to provide a drawout type isolating switch, such as disclosed in U.S. Pat. Nos. 3,264,431 and 3,264,433, and include an insulated safety shutter which automatically closes access to energized stationary line stabs. Safety shutters of some prior constructions are closed by gravity and are thereby easily or accidentally opened. Accordingly, there has been a need for an insulating shutter mechanism which prevents accidental access to the energized stationary line stabs by providing for automatic closing of access to the stabs when the isolating switch is open or withdrawn from the starter.
Associated with the foregoing has been another problem. On starters of prior construction using the isolating switch, a rear barrier, shutter, and shutter operating mechanism were part of the isolating switch. When the isolating switch was removed from the enclosure, the line stabs and vertical bus connections were completely exposed. A common practice was to display a "Danger -- High Voltage" sign and latch the doors closed. If maintenance work was required within the starter, the main horizontal bus had to be deenergized, thus shutting down all the starters in the lineup being fed from that main bus bar.